Blood lead levels lower, but tooth decay higher in children who do not drink tap water

New study published in the American Journal of Preventive Medicine explores the trade-off between higher blood lead levels and tooth decay in children who drink tap water vs bottled water

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Ann Arbor, MI, November 27, 2017

American children and adolescents who do not drink tap water, which is typically fluoridated, are much more likely to have tooth decay, according to a new study in the American Journal of Preventive Medicine. However, the study confirms that those who drink tap water are more likely to have elevated levels of lead in their blood.

Public awareness of the hazards of lead-contaminated water has increased since 2014, when concerns were raised after the drinking water source for Flint, Michigan was changed to the untreated Flint River. A federal state of emergency was declared and Flint residents were instructed to use only bottled or filtered water for drinking, cooking, cleaning, and bathing.

Even before the Flint water crisis, there was public mistrust of tap water safety. But avoiding fluoridated tap water raises another public health concern; children are denied its protection from tooth decay. According to the Centers for Disease Control and Prevention (CDC), adding fluoride to the water supply has dramatically reduced the prevalence of tooth decay over the past 70 years. However, tooth decay remains widespread. In 2011–2012, it affected the primary teeth of 23% of U.S. preschoolers.

Anne E. Sanders, PhD, and Gary D. Slade, BDSc, PhD, of the Department of Dental Ecology, University of North Carolina at Chapel Hill, analyzed a nationally representative sample of nearly 16,000 children and adolescents aged two to 19 years who participated in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2014. More than 12,000 records included data on blood lead level and about 5,600 had dental caries examination data. NHANES is the U.S. benchmark for national surveillance of blood lead levels and is the sole national source of dental examination data.

Following an in-home interview, participants visited a mobile examination center where they donated a blood sample, completed a dietary interview, and received a dental examination. About 15% of the children stated that they did not drink tap water. An elevated blood lead level was defined as having at least three micrograms of lead per deciliter of blood. Tooth decay was defined as the presence of one of more tooth surfaces affected by dental caries as determined by dental examiners using a standardized protocol.

According to the results of this study, children and adolescents who did not drink tap water were more likely than tap water drinkers to have tooth decay, but were less likely to have elevated blood lead levels. Those who drank tap water had significantly higher prevalence of elevated blood lead levels than children who did not drink tap water. Overall, nearly 3% of children and adolescents had elevated blood lead levels and 49.8% had tooth decay. Among American children and adolescents, one in five living below the federal poverty level, one in four African Americans, and one in three Mexican Americans do not drink tap water, vastly exceeding the one in twelve non-Hispanic white children who do not.

“Elevated blood lead levels affect only a small minority of children, but the health consequences are profound and permanent,” explained Sanders. “On the other hand, tooth decay affects one in every two children, and its consequences, such as toothache, are immediate and costly to treat.”

The statistical analysis took into account other factors that could account for the relationship between non-consumption of tap water and blood lead levels and tooth decay. A limitation of the study was that the fluoridation status of participants’ tap water was unknown, so the observation that drinking tap water protects against tooth decay may be an underestimate of fluoride’s protective effect.

“Our study draws attention to a critical trade-off for parents: children who drink tap water are more likely to have elevated blood lead levels, yet children who avoid tap water are more likely to have tooth decay,” commented Slade. “Community water fluoridation benefits all people, irrespective of their income or ability to obtain routine dental care. Yet we jeopardize this public good when people have any reason to believe their drinking water is unsafe.”

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Notes for EditorsThe article is “Blood Lead Levels and Dental Caries in U.S. Children Who Do Not Drink Tap Water,” by Anne E. Sanders, PhD, and Gary D. Slade, BDSC, PhD (https://doi.org/10.1016/j.amepre.2017.09.004).It will appear in the American Journal of Preventive Medicine, volume 54, issue 2 (February 2018) published by Elsevier.

The study was supported by the National Institute of Dental & Craniofacial Research of NIH under Award Number UH2DE025494.

About the American Journal of Preventive MedicineThe American Journal of Preventive Medicine is the official journal of the American College of Preventive Medicine and the Association for Prevention Teaching and Research. It publishes articles in the areas of prevention research, teaching, practice and policy. Original research is published on interventions aimed at the prevention of chronic and acute disease and the promotion of individual and community health. The journal features papers that address the primary and secondary prevention of important clinical, behavioral and public health issues such as injury and violence, infectious disease, women's health, smoking, sedentary behaviors and physical activity, nutrition, diabetes, obesity, and alcohol and drug abuse. Papers also address educational initiatives aimed at improving the ability of health professionals to provide effective clinical prevention and public health services. The journal also publishes official policy statements from the two co-sponsoring organizations, health services research pertinent to prevention and public health, review articles, media reviews, and editorials.

About ElsevierElsevier is a global information analytics business that helps institutions and professionals progress science, advance healthcare and improve performance for the benefit of humanity. Elsevier provides digital solutions and tools in the areas of strategic research management, R&D performance, clinical decision support, and professional education; including ScienceDirect, Scopus, SciVal, ClinicalKey and Sherpath. Elsevier publishes over 2,500 digitized journals, including The Lancet and Cell, more than 35,000 e-book titles and many iconic reference works, including Gray's Anatomy. Elsevier is part of RELX Group, a global provider of information and analytics for professionals and business customers across industries. www.elsevier.com